Rock-drill.



'NOT-"781,241.) f I PATENTED JAN. a1, 1905.- f Wpc. STEPHENS.

' ROCK DRILL. l PPLIOTIVOH FILED 00T.12,'1903 UNITED STATES Patented January 31, 1905.

WILLIAM CHARLES STEPHENS, OF CAMBORNE, ENGLAND.

ROCK-DRILL.

SPECIFICATION forming part of Letters-Patent N0. 781,241, dated January 31, 1905.

' i Application filed October 12 1903. Serial No. 176,686.

To @MZ whom, it may concern:

Be it known that LWILLIAM CHARLES STE- PHENS, a subject of the King of Great Britain, residing at Endsleigl1, Camborne, county of Cornwall,England,have invented new and usefulImprovements in Rock-Drills, of which the ports connected with the air-locks and allows the escape of the air therefrom, so that the air under pressure can move the valve in the re-` quired manner. The effective working of such a valve is dependent upon the said ports being retained properlyT closed until definite points of the stroke are reached; but it is.

found in practice that as the working piston wears the said ports are not completely closed,

.\so that the air escapes from the locks prematurely and reverses the valve before the stroke of\thepiston is completed. As a matter of fact,

as the "wear proceeds the stroke of 'the pistonA becomes gradually shorter and shorter, the

Ymovements of the valve becomlng more and more irregular. i

The object of my invention is to provide improvements whereby notwithstanding the wear of the istons the opening and closing f of the ports shall be properly controlled by the pistons, and to this end I provide an arrangementofV valves operated by the piston which serve to open and'close the ports in the required manner without permitting air to escape prematurely fromy the air-locks.

In ,the accompanying drawings, Figure lis a longitudinal sectionof a drill having my improvements applied to it; and Figs. 2, 3, and 4 are sectional views showing various arrangements of valve which can be made use of.

a is the cradle of the drill\;\- b, the working cylinder arranged to be traversed upon the cradle by means of the screw 0R d is the working piston, c the@ twist-gear, and f the distributing-valve,whichserves for admitting and exhausting 'the air`\into and from the two ends of the working cylinder y through the passages g g. This valve f works vina chamber f, having a passage f2, with which the air-supply pipe communicates.

In the walls'of the chamber f are two grooved channels f3 f4, which are alternately brought into communication with a groove f5 around the valve during its reciprocation. With the valve in the position shown in the drawings the channel f4 is in communication with'the air-supply, which acts on a ring-shaped surface'f around the end of the piston. When the air is allowed to escape from the opposite end of the chamber f', as hereinafter described, the pressure'o-f air upon this ringshaped space will be suliicient to push the valve over, and then the passage f3 will be placed in communication with the air-supply, so that on the release of the air from the end lirst referred to the valve will be again moved, and so on.

It L are the air-locks on the two ends of the distributing-valve, and z' t" are the passages extending to the ports j j '1, which have to be alternately opened and closed.

The simplest form of closure in connection with the said ports consists in the introduction into the said ports of bushings 7s, ol'` leather or other iiexible material, (with or without metallic linings, such as Z,). which eX- tend through the ports into contact with the ternately bring the valves into contact with As the piston wears the bush- IOO arranged in connection with seatings r r',

springs s s being arranged around the stems of the said valves for the purpose of causing them to act quickly when released by the piston.

With all the foregoing arrangements it Wiil be understood that the valves when open will project into the path of the piston sufficiently to be .acted upon by the latter during its reciprocation to close the ports to the air-locks and that, as the piston wears, the bushings, in connection with the valves, can be adjusted to compensate for this wear, whereby. notwithstanding that the piston wears, the ports to the air-locks may be tightly closed until the piston reaches the desired points in its stroke.

Having now particularly described and ascertained the nature ,of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In a rock-drill, the combination with a working cylinder and a reciprocating piston therein, of adistributing-valve casing for said cylinder provided with air-locks, and a distributing-valve in said casing, ports in the cylinder connected with passages extending to said air-locks, bushings in said ports, and movable valves having portions for directly engaging said bushings and wearing portions projecting into the cylinder in the path of the piston and adapted to be operated thereby, substantially as described.

2. In a rock-drill, the combination with a working cylinder and a reciprocating piston therein, of a distributing-valve casing for said cylinder provided with air-locks, and a distributing-valve in said casing, ports in the cylinder connected with passages extending to said air-locks, adjustable bushings in said ports and movable valves having portions for directly engaging said bushings and wearing portions projecting into the cylinder in the path of the piston, whereby the wear on said valves and said piston may be compensated by adjustment of said bushing, substantially as described.

3. In a rock-drill, the combination with a working cylinder and a reciprocating piston therein, of a distributing-valve casing for said cylinder provided with air-locks, and a distributing-valve in said casing, ports in the cylinder connected with passages extending to said air-locks, -iiexible bushings in said ports and movable valves having portions ior directly engaging said exiblc bushing and wearing portions projecting into the cylinder in the path of the piston, whereby said bushings may be forced into said ports to compensate for the wear on said valves and said piston, substantially as described.

4. In a rock-drill, the combination with a working cylinder and a reciprocating piston therein, of a distributing-val ve casing ior said cylinder provided with air-locks and a distributing-valve in said casing, ports in the cylinder connected with passages extending to said air-locks, flexible bushings in said ports, metallic linings in said bushings, movable valves having portions for directly engaging said ilexible bushings and wearing portions projecting into said cylinder in the path of the piston, whereby said bushings may be forced into said ports to compensate for the wear on said valves and piston, substantially as described.

WILLIAM CHARLES STEPHENS. 

